Introduction to ACT-R

Contents

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• 1.1 Knowledge Representations
  • chuncks
  • productions

• 1.2 The ACT-R Architecture

• 1.3 ACT-R software and Models
  • Programming Language : Common Lisp
• 1.4 Creating an ACT-R Model
  • control commands
    • clear-all
    • define-model
  • Chunk-type
    • (chunck-type chunck-name slot1 slot2 slot3)
  • Creating chuncks add-dm.
    • Example:

      (add-dm
          (b ISA counter-order first 1 second 2)
          (first-goal ISA count-from start 2 end 4)
      )
      

  • Creating productions p.
    • Example 1 : test condtions and set states of buffers or make retrieval request

        (p counting-example "example production for counting task"
           =goal>
               ISA count
               state incrementing
               number =num1           ;// "=" means it is a variable
           =retrieval>
               first =num1
               second =num2
         ==>                                 ;//  "==>" means take actions
           =goal>
             ISA count
             number =num2
           +retrieval>                    ;// "+" means make request
             ISA count-order
             first =num2
         )
      

    • Example2 : check if request fails

        (p no-carry "description:个位数加法没有产生进位"
           =goal>
             ISA add-pair
             carry busy
             ten1 =num1
             ten2 =num2
           ?retrieval>             ;// test if retrival failed
             buffer failure
         ==>
           =goal>
             carry nil              ;// eliminate a slot : set it to nil
             ten-ans busy
           +retrieval>
             addend1 =num1
             addend2 =num2
         )
      

    • Example3 : negative test use “ - “ in front of a slot on LHS, clearing buffer use “-“ on RHS ```lisp
      • (P increment =goal> ISA count-from count =num1 - end =num1 ;// “-” is the negative test modifier. =retrieval> ISA count-order first =num1 second =num2 ==> =goal> ISA count-from count =num2 +retrieval> ISA count-order first =num2 !output! (=num1) ;// to display information in the trace … ```
    • Example4 : querying the buffer itself

          ?retrieval>
             buffer   full ;// if a failure has been noted for the retrieval buffer
           ?retrieval>
             buffer   failure  ;//if there is not a chunk in the retrieval buffer
           ?retrieval>
             buffer   empty
           ?retrieval>
             buffer   requested
           ?retrieval
             buffer   unrequested
      

    • Example5: querying the buffer’s module

            ?retrieval>
                state       free
            ?retrieval>
                state       busy
            ?retrieval>
                state       error
                recently-retrieved t
      

• 1.5 The count mode
  • setting initial goal : goal-focus.
  • (goal-focus first-goal)
• 1.6 Pattern Matching Exercise
  • “Procedual”
    • Click “Why not” to debug (or use as a command)
  • “Stepper”
    • Button in the control panel to debug
• 1.7 The addition Model
  • add by count
  • 5 + 2 = 7 –> 5+1 = 6 , 5+1 = 7
  • update “sum” and “count”
  • until “count” == 2
  • output up-to-date “sum”
• 1.8 The Semantic Model
  • searching the following network to make decisions about whether one category is a member of another category.
• 1.9 Building a model following the tutorial code
  • 2-digit addition

ACT-R プログラムと普通のプログラムの違い

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• The model is not being written as commands for a computer to execute, but as commands for a cognitive processor ( a simulated human mind)

• ACT-R is a very low-level language written to run on a “processor” with many high-level capabilities built into it whereas most languages are a high-level set of operators targeting a very general low-level processor for execution.

• how the sequence of actions is determined.

  • ACT-R : order is determined based on which one currently matches the current state of the buffers and modules, and that requires satisfying all of the conditions on the LHS(left-hand side) of a production.

  • other programs : execute by the order as written.

  • optimizations and efficient design metrics which are important in normal programming tasks, like efficient algorithms, code reuse, minimal number of steps, etc, are not always good design choices for creating an ACT-R model because such models will not perform “like a person”. Instead, one has to consider the task from a human perspective and rely on psychological research and performance data to guide the design of the model.